The Competition Commission said it initiated an investigation against Aspen for suspected abuse of dominance by charging excessive prices in the provision of lifesaving cancer medicine in South Africa.

"This is a matter of grave national importance and we have decided that we would announce it [the investigation] so that we get everybody aware that we are conducting these investigations so they may submit information to us".

Tembinkosi Bonakele, head of the Competition Commission, said the agency would investigate Aspen Pharmacare, Africa's biggest generic drug maker, USA company Pfizer and Swiss-based Roche Holding.

The Swiss giant said it had not yet been notified of the investigation.

Roche sells trastuzumab as Herceptin and Herclon in South Africa.

"The commission has reason to believe that Roche and its USA-based biotechnology company, Genentech, have and continue to engage in excessive pricing, price discrimination... in the provision of breast cancer medicine in South Africa", it said in a statement.

Roche said in an email it had not received a formal notification from the Commission when asked for comment.

Roche is under investigation for breast cancer drug pricing, according to the commission, while Pfizer's lung cancer drug pricing is included in the inquiry. It also suspects a similar anticompetitive conduct for breast cancer drugs sold by Roche.

Aspen is undergoing a legal process with European regulators over allegations that the company secretly planned to destroy life-saving cancer medication European countries to allow price hikes, Fin24 reported.